Methods of optical device fabrication using an electron beam apparatus

ABSTRACT

Aspects of the disclosure relate to apparatus for the fabrication of waveguides. In one example, an angled ion source is utilized to project ions toward a substrate to form a waveguide which includes angled gratings. In another example, an angled electron beam source is utilized to project electrons toward a substrate to form a waveguide which includes angled gratings. Further aspects of the disclosure provide for methods of forming angled gratings on waveguides utilizing an angled ion beam source and an angled electron beam source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 62/780,805, filed Dec. 17, 2018, and U.S. provisional patentapplication Ser. No. 62/780,792, filed Dec. 17, 2018, both of which areherein incorporated by reference in their entirety.

BACKGROUND Field

Embodiments of the disclosure generally relate to apparatus and methodsfor optical device fabrication. More specifically, embodiments of thedisclosure relate to apparatus and methods for ion beam and electronbeam waveguide fabrication.

Description of the Related Art

Virtual reality is generally considered to be a computer generatedsimulated environment in which a user has an apparent physical presence.A virtual reality experience can be generated in three dimensions (3D)and viewed with a head-mounted display (HMD), such as glasses or otherwearable display devices that have near-eye display panels as lenses todisplay a virtual reality environment that replaces an actualenvironment.

Augmented reality, however, enables an experience in which a user canstill see through the display lenses of the glasses or other HMD deviceto view the surrounding environment, yet also see images of virtualobjects that are generated for display and appear as part of theenvironment. Augmented reality can include any type of input, such asaudio and haptic inputs, as well as virtual images, graphics, and videothat enhances or augments the environment that the user experiences. Asan emerging technology, there are many challenges and design constraintswith augmented reality.

One such challenge is displaying a virtual image overlayed on an ambientenvironment. Waveguides are used to assist in overlaying images.Generated light propagates through a waveguide until the light exits thewaveguide and is overlayed on the ambient environment. Fabricatingwaveguides can be challenging as waveguides tend to have non-uniformproperties. Accordingly, what is needed in the art are improved methodsand systems of waveguide fabrication

SUMMARY

In one embodiment, a waveguide fabrication method is provided. Themethod includes positioning a substrate on a pedestal in a processvolume of a chamber and positioning the pedestal opposite a segmentedsurface of an electrode. The segmented surface includes a plurality ofangled surfaces and electrons are projected from the segmented surfaceof the electrode toward the substrate at one or more non-normal anglesto form angled fins on the substrate.

In another embodiment, a waveguide fabrication method is provided. Themethod includes positioning a substrate on a pedestal in a processvolume of a chamber and positioning the pedestal opposite a segmentedsurface of an electrode. The segmented surface includes a plurality ofangled surfaces having a substantially uniform morphology. A plasma isgenerated in the process volume and electrons are projected from thesegmented surface of the electrode toward the substrate at one or morenon-normal angles to form angled fins on the substrate.

In yet another embodiment, a waveguide fabrication method is provided.The method includes positioning a substrate on a pedestal in a processvolume of a chamber and positioning the pedestal opposite a segmentedsurface of an electrode. The segmented surface includes a plurality ofangled surfaces having different morphologies and differing in at leastone of size, shape, spacing, density, or distribution across thesegmented surface. A plasma is generated in the process volume andelectrons are projected from the segmented surface of the electrodetoward the substrate at one or more non-normal angles to form angledfins on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofits scope, and may admit to other equally effective embodiments.

FIG. 1 illustrates a plan view of a waveguide combiner according to anembodiment of the disclosure.

FIG. 2 illustrates a schematic side view of an angled etch systemaccording to an embodiment of the disclosure.

FIG. 3 illustrates a side sectional view of an electrode assemblyaccording to an embodiment of the disclosure.

FIG. 4A illustrates a schematic side view of a segmented ion sourceaccording to an embodiment of the disclosure.

FIG. 4B illustrates a schematic side view of a segmented ion sourceaccording to an embodiment of the disclosure.

FIG. 4C illustrates a schematic side view of a segmented ion sourceaccording to an embodiment of the disclosure.

FIG. 5A illustrates a schematic plan view of a filter plate according toan embodiment of the disclosure.

FIG. 5B illustrates a schematic side view of the segmented ion source ofFIG. 4C with filter plates coupled thereto according to an embodiment ofthe disclosure.

FIG. 6 illustrates a schematic cross-sectional view of an electron beametching system according to an embodiment of the disclosure.

FIG. 7A illustrates an angled etching process performed on a waveguideat a first position according to an embodiment of the disclosure.

FIG. 7B illustrates the waveguide of FIG. 7A during the angled etchingprocess at a second position according to an embodiment of thedisclosure.

FIG. 8 illustrates operations of a method for etching a waveguide withan angled ion beam according to an embodiment of the disclosure.

FIG. 9 illustrates operations of a method for etching a waveguide withan angled electron beam according to an embodiment of the disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Aspects of the disclosure relate to apparatus for the fabrication ofnanostructured optical devices, such as waveguides, waveguide combiners,angled gratings, and metalenses, for use in a variety of devices, suchas headsets for augmented reality/virtual reality (AR/VR) and smartwindows. In one example, an angled ion source is utilized to projections toward a substrate to form a waveguide which includes angledgratings. In another example, an angled electron beam source is utilizedto project electrons toward a substrate to form a waveguide whichincludes angled gratings. Further aspects of the disclosure provide formethods of forming angled gratings on waveguides utilizing an angled ionbeam source and an angled electron beam source.

FIG. 1 illustrates a plan view of a waveguide combiner 100 according toan embodiment of the disclosure. It is to be understood that thewaveguide combiner 100 described below is an exemplary waveguidecombiner and other waveguide combiners having different designs maybenefit from the embodiments described herein. The waveguide combiner100 includes an input coupling region 102 defined by a plurality ofgratings 108, an intermediate region 104 defined by a plurality ofgratings 110, and an output coupling region 106 defined by a pluralityof gratings 112. The input coupling region 102 receives incident beamsof light (a virtual image) having an intensity from a microdisplay. Eachgrating, such as a fin structure or the like, of the plurality ofgratings 108 splits the incident beams into a plurality of modes, eachbeam having a mode. Zero-order mode (T0) beams are reflected back ortransmitted through the waveguide combiner 100, positive first-ordermode (T1) beams are coupled though the waveguide combiner 100 to theintermediate region 104, and negative first-order mode (T−1) beamspropagate in the waveguide combiner 100 a direction opposite to the T1beams. Ideally, the incident beams are split into T1 beams that have allof the intensity of the incident beams in order to direct the virtualimage to the intermediate region 104. One approach to split the incidentbeam into T1 beams that have all of the intensity of the incident beamsis to utilize fins, which comprise the gratings 108, having a slantangle to suppress the T−1 beams and the T0 beams. The T1 beams undergototal-internal-reflection (TIR) through the waveguide combiner 100 untilthe T1 beams come in contact with the plurality of gratings 110 in theintermediate region 104. A portion of the input coupling region 102 mayhave gratings 108 with a slant angle different than the slant angle ofgratings 108 from an adjacent portion of the input coupling region 102.

The T1 beams contact a fin of the plurality of gratings 110. The T1beams are split into T0 beams refracted back or lost in the waveguidecombiner 100, T1 beams that undergo TIR in the intermediate region 104until the T1 beams contact another fin of the plurality of gratings 110,and T-1 beams that are coupled through the waveguide combiner 100 to theoutput coupling region 106. The T1 beams that undergo TIR in theintermediate region 104 continue to contact gratings of the plurality ofgratings 110 until the either the intensity of the T1 beams coupledthrough the waveguide combiner 100 to the intermediate region 104 isdepleted, or remaining T1 beams propagating through the intermediateregion 104 reach the end of the intermediate region 104.

The plurality of gratings 110 are tuned to control the T1 beams coupledthrough the waveguide combiner 100 to the intermediate region 104 tocontrol the intensity of the T−1 beams coupled to the output couplingregion 106 to modulate a field of view of the virtual image producedfrom the microdisplay from a user's perspective and increase a viewingangle from which a user can view the virtual image. One approach tocontrol the T1 beams coupled through the waveguide combiner 100 to theintermediate region 104 is to optimize the slant angle of each fin ofthe plurality of gratings 110 to control the intensity of the T−1 beamscoupled to the output coupling region 106. A portion of the intermediateregion 104 may have gratings 110 with a slant angle different than theslant angle of gratings 110 from an adjacent portion of the intermediateregion 104. Furthermore, the gratings 110 may have fins with slantangles different than the slant angles of fins of the gratings 108.

The T−1 beams coupled through the waveguide combiner 100 to the outputcoupling region 106 undergo TIR in the waveguide combiner 100 until theT−1 beams contact a grating of the plurality of gratings 112 where theT−1 beams are split into T0 beams refracted back or lost in thewaveguide combiner 100. T1 beams that undergo TIR in the output couplingregion 106 until the T1 beams contact another fin of the plurality ofgratings 112 and T−1 beams coupled out of the waveguide combiner 100.The T1 beams that undergo TIR in the output coupling region 106 continueto contact fins of the plurality of gratings 112 until either theintensity of the T−1 beams coupled through the waveguide combiner 100 tothe output coupling region 106 is depleted or remaining T1 beamspropagating through the output coupling region 106 have reached the endof the output coupling region 106. The plurality of gratings 112 aretuned to control the T−1 beams coupled through the waveguide combiner100 to the output coupling region 106 in order to control the intensityof the T−1 beams coupled out of the waveguide combiner 100 to furthermodulate the field of view of the virtual image produced from themicrodisplay from the user's perspective and further increase theviewing angle from which the user can view the virtual image.

One approach to control the T−1 beams coupled through the waveguidecombiner 100 to the output coupling region 106 is to optimize the slantangle of each fin of the plurality of gratings 112 to further modulatethe field of view and increase the viewing angle. A portion of theintermediate region 104 may have gratings 110 with a fin slant angledifferent than the slant angle of fins of the gratings 110 from anadjacent portion of the intermediate region 104. Furthermore, thegratings 112 may have fin slant angles different that the fin slantangles of the gratings 108 and the gratings 110.

FIG. 2 illustrates a schematic side view of an angled etch system 200according to an embodiment of the disclosure. It is to be understoodthat the angled etch system 200 described below is an exemplary angledetch system and other angled etch systems may be used with or modifiedto fabricate waveguide combiners in accordance with the embodiments ofthe disclosure.

To form fins having slant angles, a grating material 212 disposed on asubstrate 210 is etched by the angled etch system 200. In oneembodiment, the grating material 212 is disposed on an etch stop layer211 disposed on the substrate 210 and a patterned hardmask 213 isdisposed over the grating material 212. The materials of gratingmaterial 212 are selected based on the slant angle ϑ of each fin and therefractive index of the substrate 210 to control the in-coupling andout-coupling of light and facilitate light propagation through awaveguide combiner. In another embodiment, the grating material 212includes silicon oxycarbide (SiOC), titanium dioxide (TiO₂), silicondioxide (SiO₂), vanadium (IV) oxide (VOx), aluminum oxide (Al₂O₃),indium tin oxide (ITO), zinc oxide (ZnO), tantalum pentoxide (Ta₂O₅),silicon nitride (Si₃N₄), titanium nitride (TiN), and/or zirconiumdioxide (ZrO₂) containing materials. The grating material 212 has arefractive index between about 1.5 and about 2.65.

In another embodiment, which may be combined with other embodimentsdescribed herein, the patterned hardmask 213 is a non-transparenthardmask that is removed after the waveguide combiner is formed. Forexample, the non-transparent hardmask includes reflective materials,such as chromium, silver, titanium nitride, tantalum nitride, siliconnitride, or silicon oxide materials. In another embodiment, thepatterned hardmask 213 is a transparent hardmask. In one embodiment,which may be combined with other embodiments described herein, the etchstop layer 211 is a non-transparent etch stop layer that is removedafter the waveguide combiner is formed. In another embodiment, which maybe combined with other embodiments described herein, the etch stop layer211 is a transparent etch stop layer.

The angled etch system 200 includes an ion beam chamber 202 that housesan ion beam source 204. The ion beam source 204 is configured togenerate an ion beam 216, such as a spot beam, a ribbon beam, or a fullsubstrate-size beam. The ion beam chamber 202 is configured to directthe ion beam 216 at an angle α relative to a datum plane 218 orientednormal to the substrate 210. For example, the system 200 also includes asegmented source 230. The segmented source 230 modulates the angle ofthe ion beam 216 to achieve the angle α utilized to fabricate the finsin the grating material 212. The segmented source 230, which may includea plurality of segments, each including one or more electrodes, isdescribed in detail with regard to FIG. 3 and FIGS. 4A-4C.

The substrate 210 is retained on a platen 206 coupled to a firstactuator 208. The first actuator 208, which may be a linear actuator, arotary actuator, a stepper motor, or the like, is configured to move theplaten 206 in a scanning motion along a y-direction and/or az-direction. In one embodiment, the first actuator 208 is furtherconfigured to tilt the platen 206 such that the substrate 210 ispositioned at a tilt angle β relative to the x-axis of the ion beamchamber 202. The angle α and tilt angle β result in an ion beam angle ϑrelative to the datum plane 218. To form fins having a slant angle ϑ′relative the datum plane 218, the ion beam source 204 generates an ionbeam 216 and the ion beam chamber 202 directs the ion beam 216 throughthe segmented source 230 towards the substrate 210 at the angle α. Thefirst actuator 208 positions the platen 206 so that the ion beam 216contacts the grating material 212 at the ion beam angle ϑ and etchesfins having a slant angle ϑ′ on desired portions of the grating material212. A second actuator 220 may also be coupled to the platen 206 torotate the substrate 210 about the x-axis of the platen 206 to controlthe slant angle ϑ′ of gratings. Advantageously, various differentregions of the substrate 210 may be exposed to the ion beam 216 byrotating the substrate 210 without otherwise changing apparatus of theion beam chamber 202.

FIG. 3 illustrates a side sectional view of an electrode assembly 300according to an embodiment of the disclosure. In one embodiment, theelectrode assembly 300 may be adapted as a graded lens configuration. Inanother embodiment, which may be combined with other embodiments, theelectrode assembly 300 includes one or more assemblies of electrodes.For example, the electrode assembly 300 may include a set of entranceelectrodes 302, one or more sets of suppression electrodes 304 (orfocusing electrodes), and a set of exit electrodes 306. The exitelectrodes 306 may be referred to as ground electrodes. Each set ofelectrodes 302, 304, 306 may be positioned with a space or gap to enablepassage or an ion beam 216 (e.g., a ribbon beam, a spot beam, or fullsubstrate-size beam) therethrough.

In some embodiments, the entrance electrodes 302, the suppressionelectrodes 304, and the exit electrodes 306 are be provided in a housing308. A pump 310 may be directly or indirectly connected to the housing308. The pump 310 may be a vacuum pump for providing a high-vacuumenvironment or other controlled environment of a different pressure. Forexample, the pump 310 may generate a subatmospheric pressure environmentwithin the housing 308 or the pump 310 may maintain an approximatelyatmospheric pressure environment within the housing 308. In otherembodiments, which may be combined with other embodiments, the housing308 may include one or more dielectric members 314. The dielectricmembers 314 function to electrically isolate the housing 308 from othercomponents of the electrode assembly 300.

The set of entrance electrodes 302 and exit electrodes 306 may includetwo conductive pieces electrically coupled to each other. In otherembodiments, the assembly of entrance electrodes 302 are a single-piecestructure with an aperture for the ion beam 216 to pass therethrough. Insome embodiments, upper and lower portions of suppression electrodes 304may have different potentials (e.g., in separate/discreet conductiveportions) in order to deflect the ion beam 216 passing therethrough.Although the electrode assembly 300 is depicted as a seven (7) elementlens configuration (e.g., with five (5) sets of suppression electrodes304), it should be appreciated that any number of elements (orelectrodes) may be utilized. For example, in some embodiments, theelectrode assembly 300 may utilize a range of three (3) to ten (10)electrode sets.

Electrostatic focusing of the ion beam 216 may be achieved by usingseveral thin electrodes (e.g., the suppression electrodes 304) tocontrol grading of potential along a path the ion beam 216. As a result,the use of input ion beams 216 may be used in an energy range, such as100 Volts to 3,000 Volts, that may enable higher-quality beams, even forvery low energy output beams. In one embodiment, as the ion beam 216passes through the electrodes of the electrode assembly 300, the ionbeam 216 may be decelerated from 6 keV to 0.2 keV and deflected at about15 degrees to about 30 degrees, or greater, by the electrodes of theelectrode assembly 300. In one example, the energy ratio may be 30/1.

It should be appreciated that separating and independently controllingdeceleration, deflection, and/or focus may be accomplished by one or acombination of moving the electrodes (e.g., the entrance electrode 302,suppression electrodes 304, and the exit electrode 306) with respect toa central ray trajectory (e.g. the datum plane 218 of FIG. 2) of the ionbeam 216, and varying deflection voltages electrodes (e.g., the entranceelectrode 302, suppression electrodes 304, and the exit electrode 306)along the central ray trajectory of the ion beam 216 to reflect beamenergy at each point along the central ray trajectory at a deflectionangle α. The symmetry of the electrodes with respect to the central raytrajectory of the ion beam 216 is where the ends of upper and lowerelectrodes closest to the ion beam 216 may be maintained at equal (ornear-equal) perpendicular distances from the central ray trajectory ofthe ion beam 216. For example, a difference in voltages on electrodesabove and below the ion beam 216 may be configured so that a deflectioncomponent of the electric field may be a fixed ratio/factor of the beamenergy at that point (which may vary along the electrodes or lenses).

FIG. 4A illustrates a schematic side view of a segmented ion source 230according to an embodiment of the disclosure. The segmented ion source230 is coupled to or otherwise integrated with the ion beam chamber 202and segments 412 of the segmented ion source 230 are aligned orotherwise positioned to receive the ion beam 216 from the beam source204.

The segmented ion source 230 includes a housing 402 having a first wall404, a second wall 406, a third wall 414, and a fourth wall 416. In oneembodiment, the first wall 404 and second wall 406 are orientedsubstantially parallel to one another. The third wall 414 and fourthwall 416 are also substantially parallel to one another and extendbetween the first wall 404 and the second wall 406. While theabove-described orientation of walls 404, 406, 414, 416 may bebeneficially employed, it is contemplated that other wall configurationsmay be utilized.

In one embodiment, the first wall 404 is coupled to the ion beam chamber202 and the segments 412 are positioned adjacent to and opposite theplaten 206. The segments 412 are formed in the second wall 406 andinclude a plurality of surfaces 408, 410. A first surface 408 is angledrelative to a datum plane defined by the second wall 406. The angle ofthe first surface 408 may be selected between about 1 degree and about60 degrees from the datum plane defined by the second wall 406. Thus,the first surface 408 extends from the second wall 406 and an angle intothe housing 402 and toward the first wall 404.

A second surface 410 extends between the first surface 408 and thesecond wall 406. The second surface 410 is oriented substantially normalto the datum plane defined by the second wall 406. However, it iscontemplated that the second surface 410 may be oriented at non-normalangles with respect to the datum plane defined by the second wall 406.While three segments 412 are illustrated, it is contemplated that agreater or lesser number of segments 412 may be utilized to modulate theion beam 216 depending upon the area of the substrate 210 desired to beetched. Additionally, it is contemplated that the magnitude of thesurfaces 408, 410 may be changed relative to one another to modulateangle characteristics of the ion beam 216.

In one embodiment, the electrode assembly 300 is positioned within thehousing 402 adjacent to the first surface 408 of the second wall 406.For example, the electrode assembly 300 may be coupled to the firstsurface 408 within the housing 402. As depicted in FIG. 3, the housing308 of the electrode assembly 300 may include a shape selected to matchor interface with the angle of the first surface 408. The first surface408 may also include one or more openings 418 therein adjacent to wherethe electrode assembly 300 is positioned to enable the ion beam 216 topass through the first surface 408. Similarly, the first wall 404 mayalso have one or more openings 420 formed therein and the openings 420formed in the first wall 404 may be aligned with one or both of theopenings 418 formed in the first surface 408 or the electrode assembly300. Accordingly, the ion beam 216 may propagate through the first wall404 at an orientation substantially normal to a datum plane defined bythe first wall 404 but exit the housing 402 through the first surface408 of the second wall 406 at a predetermined angle.

FIG. 4B illustrates a schematic side view of a segmented ion source 230according to an embodiment of the disclosure. The segmented ion source230 is coupled to or otherwise integrated with the ion beam chamber 202and segments 412 of the segmented ion source 230 are aligned orotherwise positioned to receive the ion beam 216 from the beam source204.

The segmented ion source 230 includes a housing 422 having a first wall424, a second wall 426, a third wall 434, and a fourth wall 436. In oneembodiment, the first wall 424 and second wall 426 are orientedsubstantially parallel to one another. The third wall 434 and fourthwall 436 are also substantially parallel to one another and extendbetween the first wall 424 and the second wall 426. While theabove-described orientation of walls 424, 426, 434, 436 may bebeneficially employed, it is contemplated that other wall configurationsmay be utilized.

In one embodiment, the first wall 424 is coupled to the ion beam chamber202 and the segments 412 are positioned adjacent to and opposite theplaten 206. The segments 412 are formed in the second wall 426 andinclude a plurality of surfaces 428, 430, 432. A first surface 428 isangled relative to a datum plane defined by the second wall 426. Theangle of the first surface 428 may be selected between about 1 degreeand about 60 degrees from the datum plane defined by the second wall426. Thus, the first surface 428 extends from the second wall 426 and anangle into the housing 422 and toward the first wall 424.

A second surface 430 extends between the first surface 428 and a thirdsurface 432. The second surface 430 is oriented substantially parallelto the datum plane defined by the second wall 426. However, it iscontemplated that the second surface 430 may be oriented at non-parallelangles with respect to the datum plane defined by the second wall 426.The third surface 432 extends from the second surface 430 to the secondwall 426 at an adjacent first surface 428. The third surface 432 isangled with respect to the datum plan defined by the second wall 426. Inone example, the angle of the third surface 432 is substantially similarto the angle of the first surface 428. Alternatively, the angle of thethird surface 432 may be different from the angle of the first surface428. The magnitude of the second surface 430 spaces the third surface432 from the first surface 428. Accordingly, it is contemplated that thefirst surface 428 may be oriented at a wider range of angles to enableangled etching of the substrate 210. Additionally, the spacing andorientation of the third surface 432 from the first surface 428 isbelieved to enable a larger area of the substrate 210 to be processed ata time. While three segments 412 are illustrated, it is contemplatedthat a greater or lesser number of segments 412 may be utilized tomodulate the ion beam 216 depending upon the area of the substrate 210desired to be etched. It is also contemplated that the magnitude of thesurfaces 428, 430, 432 may be changed relative to one another tomodulate angle characteristics of the ion beam 216.

In one embodiment, the electrode assembly 300 is positioned within thehousing 422 adjacent to the first surface 428 of the second wall 426.For example, the electrode assembly 300 may be coupled to the firstsurface 428 within the housing 422. As depicted in FIG. 3, the housing308 of the electrode assembly 300 may include a shape selected to matchor interface with the angle of the first surface 428. The first surface428 may also include one or more openings 438 therein adjacent to wherethe electrode assembly 300 is positioned to enable the ion beam 216 topass through the first surface 428. Similarly, the first wall 424 mayalso have one or more openings 440 formed therein and the openings 440formed in the first wall 424 may be aligned with one or both of theopenings 438 formed in the first surface 428 or the electrode assembly300. Accordingly, the ion beam 216 may propagate through the first wall424 at an orientation substantially normal to a datum plane defined bythe first wall 424 but exit the housing 422 through the first surface428 of the second wall 426 at a predetermined angle.

FIG. 4C illustrates a schematic side view of a segmented ion source 230according to an embodiment of the disclosure. The segmented ion source230 is coupled to or otherwise integrated with the ion beam chamber 202and segments 412 of the segmented ion source 230 are aligned orotherwise positioned to receive the ion beam 216 from the beam source204.

The segmented ion source 230 includes a housing 442 having a first wall444, a second wall 446, a third wall 454, and a fourth wall 456. In oneembodiment, the first wall 444 and second wall 446 are orientedsubstantially parallel to one another. The third wall 454 and fourthwall 456 are also substantially parallel to one another and extendbetween the first wall 444 and the second wall 446. While theabove-described orientation of walls 444, 446, 454, 456 may bebeneficially employed, it is contemplated that other wall configurationsmay be utilized.

In one embodiment, the first wall 444 is coupled to the ion beam chamber202 and the segments 412 are positioned adjacent to and opposite theplaten 206. The segments 412 are formed in the second wall 446 andinclude a plurality of surfaces 448, 450, 452. A first surface 428 isangled relative to a datum plane defined by the second wall 446. Theangle of the first surface 448 may be selected between about 1 degreeand about 60 degrees from the datum plane defined by the second wall446.

A second surface 450 extends between the first surface 448 and a thirdsurface 452. The second surface 450 is oriented substantially parallelto the datum plane defined by the second wall 446. However, it iscontemplated that the second surface 450 may be oriented at non-parallelangles with respect to the datum plane defined by the second wall 446.The third surface 452 extends from the second wall 446 at a non-normalangle relative to the datum plane defined by the second wall 446. Inthis embodiment, the third surface 452 extends from the second wall 446at an angle out of the housing 422 and away the first wall 444.Alternatively, the third surface 452 may extend from the second wall 446at an angle normal to the datum plane defined by the second wall 446.

In one example, the angle of the third surface 452 is substantiallysimilar to the angle of the first surface 448. Alternatively, the angleof the third surface 452 may be different from the angle of the firstsurface 448. The magnitude of the second surface 450 spaces the thirdsurface 452 from the first surface 448. Accordingly, it is contemplatedthat the first surface 448 may be oriented at a wider range of angles toenable angled etching of the substrate 210. Additionally, the spacingand orientation of the third surface 452 from the first surface 448 isbelieved to enable a larger area of the substrate 210 to be processed ata time. While three segments 412 are illustrated, it is contemplatedthat a greater or lesser number of segments 412 may be utilized tomodulate the ion beam 216 depending upon the area of the substrate 210desired to be etched. It is also contemplated that the magnitude of thesurfaces 448, 450, 452 may be changed relative to one another tomodulate angle characteristics of the ion beam 216.

In one embodiment, the electrode assembly 300 is positioned within thehousing 442 adjacent to the first surface 448 of the second wall 446.For example, the electrode assembly 300 may be coupled to the firstsurface 448 within the housing 442. As depicted in FIG. 3, the housing308 of the electrode assembly 300 may include a shape selected to matchor interface with the angle of the first surface 448. The first surface448 may also include one or more openings 458 therein adjacent to wherethe electrode assembly 300 is positioned to enable the ion beam 216 topass through the first surface 448. Similarly, the first wall 444 mayalso have one or more openings 460 formed therein and the openings 460formed in the first wall 444 may be aligned with one or both of theopenings 458 formed in the first surface 448 or the electrode assembly300. Accordingly, the ion beam 216 may propagate through the first wall444 at an orientation substantially normal to a datum plane defined bythe first wall 444 but exit the housing 442 through the first surface448 of the second wall 446 at a predetermined angle.

The segmented ion source 230 coupled to the ion beam chamber 202utilizes the segments 412 and electrode assembly 300 to modulate theangle of the ion beam 216 generated by the beam source 204. The segments412 and electrode assembly 300 may be positioned or otherwise orientedin a manner to enable angled etching of the substrate 210. It iscontemplated that the segmented ion source 230 may be modular in natureand different segmented ion sources may be interchanged on the ion beamchamber 202 to facilitate different angled etching profiles of thesubstrate 210. The segmented ion source 230 may also be utilized toreduce processing complexity associated with movement of the platen 206by reducing variables associated with movement of the platen 206 by theactuators 208, 220. The segmented ion source 230 may also be utilized incombination with movement of the platen 206 via the actuators 208, 220to enable more complex or precise angled etching profiles of thesubstrate 210.

FIG. 5A illustrates a schematic, plan view of a filter plate 500according to an embodiment of the disclosure. FIG. 5B illustrates aschematic side view of the segmented ion source 230 of FIG. 3C withfilter plates 500 coupled thereto according to an embodiment of thedisclosure. The filter plate 500 is adapted to interface with and coupleto the segmented ion source 230 to modulate the intensity ordistribution of the ion beam 216 passing through the filter plate 500.

The filter plate 500 includes a body 502 having a plurality of apertures506, 510, 514 formed therein. The body 502 is fabricated from a materialof sufficient thickness which is resistant or inert to ion beambombardment and prevents ions from passing threrethrough. The apertures506, 510, 514 extend through the body 502 to form openings through whichthe ion beam 216 passes. A first region 504 of the body 502 includes afirst plurality of apertures 506. Although the first region 504 isillustrated as occupying approximately one third of the body 502, it iscontemplated that the first region 504 may include a greater or lesserportion of the body 502. The first plurality of apertures 506 areillustrated as being substantially circle-shaped with an approximatelyeven distribution between adjacent apertures of the first plurality ofapertures 506. However, any number, shape, orientation, spacing, orarrangement of the first plurality of apertures 506 may be utilized tomodulate the intensity or distribution of the ion beam 216 passingthrough the first plurality of apertures 506.

A second region 508 of the body 502 includes a second plurality ofapertures 510. Although the second region 508 is illustrated asoccupying approximately one third of the body 502, it is contemplatedthat the second region 508 may include a greater or lesser portion ofthe body 502. The second plurality of apertures 510 are illustrated asbeing substantially oval-shaped with an approximately even distributionbetween adjacent apertures of the second plurality of apertures 510.However, any number, shape, orientation, spacing, or arrangement of thesecond plurality of apertures 510 may be utilized to modulate theintensity or distribution of the ion beam 216 passing through the secondplurality of apertures 510.

A third region 512 of the body 502 includes a third plurality ofapertures 514. Although the third region 512 is illustrated as occupyingapproximately one third of the body 502, it is contemplated that thethird region 512 may include a greater or lesser portion of the body502. The third plurality of apertures 514 are illustrated as beingsubstantially circle-shaped with an approximately even distributionbetween adjacent apertures of the third plurality of apertures 514.However, any number, shape, orientation, spacing, or arrangement of thethird plurality of apertures 514 may be utilized to modulate theintensity or distribution of the ion beam 216 passing through the thirdplurality of apertures 514.

In one example, the first plurality of apertures 506 occupy an area ofthe body 502 in the first region 504 which is greater than an area ofeither the second plurality of apertures 510 and/or the third pluralityof apertures 514. In other words, the ion beam 216 passing through thefirst region 504 of the body 502 is less obstructed when compared to thesecond region 508 and/or the third region 512. Thus, the ion beam 216passing through the first region 504 may contact a first region of thesubstrate 210 with a greater amount and intensity of ions. The secondregion 508 and third region 512 have different arrangements, spacing,and shapes of apertures 510, 514, respectively, and modulate the ionbeam 216 passing threrethrough such that the amount and intensity ofions contacting the substrate 210 in second and third regions,respectively, are different from the amount and intensity of ions whichwere modulated by the first region 504.

In one example, an angled etching profile on the substrate 210 in afirst region is generated by the ion beam 216 passing through the firstplurality of apertures 506, an angled etching profile on the substrate210 in a second region is generated by the ion beam 216 passing throughthe second plurality of apertures 510, and an angles etching profile onthe substrate 210 in a third region is generated by the ion beam 216passing through the third plurality of apertures 514. The differentetching profiles of fins or gratings formed on the substrate aregenerated by the regions 514, 518, 518 of the filter plate 500. It iscontemplated that various aperture designs, shapes, spacing, density,etc. incorporated in the filter plate 500 may be utilized to modulatethe ion beam 216 characteristics and thus enable different angledetching profiles on a substrate while utilizing a single ion beamchamber 202 and/or ion beam source 204.

FIG. 5B illustrates a schematic side view of the segmented ion source230 of FIG. 4C with filter plates 500 coupled thereto according to anembodiment of the disclosure. The filter plates 500 are coupled to thefirst surface 448 of the segmented ion source 230. The filter plates 500may be coupled to the first surface 448 by mechanical fasteningapparatus, such as bolts, screws, or the like, or may be integrated intothe first surface 448 such that the first surface 448 and the filterplate 500 is a unitary structure. In one embodiment, the filter plates500 are disposed at an angle relative to the datum plane defined by thesecond wall 446. The electrode assemblies 300 are disposed within thehousing 442 adjacent to the first surface 448. The ion beam 216 enteringthe opening 460 is modulated, curved, or angled by the electrodeassemblies 300 and the angled ion beam 216 passes through the opening458 where the ion beam 216 is modulated in intensity and/or distributionby the filter plates 500. It is contemplated that the ion beam 216,which has been modulated by the filter plate 500, has a plurality ofdifferent characteristics which etch the substrate 210 differentlydepending upon which region 504, 508, 512 of the filter plate 500 theion beam 216 passes through. Such different etching profiles andcharacteristics enabled by the filter plate 500 may be utilized to etchfins or gratings on the substrate 210 with different depths or othercharacteristics.

While the segmented ion source 230 of FIG. 4C is illustrated with thefilter plates 500, it is contemplated that the filter plates 500 may beadvantageously utilized in combination with the segmented ion source 230of FIGS. 4A and 4B. For example, the filter plate 500 may be coupled tothe first surface 408 of the segmented ion source 230 of FIG. 4A or thefilter plate 500 may be coupled to the first surface 428 of thesegmented ion source 230 of FIG. 4B. Depending upon the configuration ofthe segmented ion source 230, the filter plate 500 and the electrodeassembly 300 may be disposed in various different orientations thanthose illustrated. For example, the electrode assembly 300 and filterplate 500 may be utilized on opposing sides of the third surfaces 432,452 of the segmented ion source 230 of FIG. 4B and FIG. 4C,respectively.

FIG. 6 illustrates a schematic, cross-sectional view of an electron beametching system 600 according to an embodiment of the disclosure. Oneexample of an electron beam etching system 600 is the SYM3™ apparatusavailable from Applied Materials, Inc., Santa Clara, Calif., which maybe modified in accordance with various aspects of the disclosure. It iscontemplated that other suitable apparatus from other manufacturers mayalso benefit from the embodiments described herein.

The system 600 includes a chamber body 602 which encloses or otherwisedefines a process volume 640. The chamber body 602 may be fabricatedfrom suitable materials such as stainless steel, aluminum, or alloys andcombinations thereof. A first liner 636 is disposed adjacent to thechamber body 602 to protect the chamber body 602 from the processingenvironment of the process volume 640. In one example, the first liner636 may be fabricated from process inert or resistant materials, such asa ceramic material or other suitable materials, for example, siliconcontaining material, carbon containing material, silicon carbonmaterial, or silicon oxide containing materials.

A second liner 638 is also disposed adjacent to the chamber body 602 andthe second liner 638 is positioned to substantially surround the processvolume 640. In one embodiment, the second liner 638 is fabricated from adielectric material, such as quartz or a ceramic material. In anotherembodiment, the second line 638 is fabricated from materials similar tothose utilized to fabricate the first liner 636. The liners 636, 638 mayalso be coated with various materials similar to those utilized tofabricate the liners 636, 638 and may additionally be coated withmaterials such as aluminum oxide materials, yttrium oxide materials, orzirconium materials. In certain embodiments, one or both of the firstliner 636 and the second liner 638 are optional. In such embodiments,the chamber body 602 may be fabricated and configured to functionwithout liners.

An exhaust port 648 is formed through the second liner 636 and thechamber body 602. The exhaust port 648 is formed through the secondliner 636 and the chamber body 602 as a location below a pedestal 604disposed in the process volume 640. A pump 650 is in fluid communicationwith the process volume 640 via the exhaust port 648 and a pump port 646which surrounds the pedestal 604. The pump 650 enables exhausting ofmaterials from the process volume 640. A lid 616 is coupled to orotherwise integrated with the chamber body 602 opposite the pedestal604.

The pedestal 604 includes an electrode 606 disposed therein. In oneembodiment, the electrode 606 is a chucking apparatus, such as anelectrostatic chuck, for securing a substrate 614 thereto duringprocessing of the substrate 614. A conduit 610, such as an electricalconduit or the like, is coupled between the electrode 606 and a powersource 612. Power from the power source 612 may be utilized to bias theelectrode 606 to either chuck the substrate 614 to the electrode 606 orinfluence bombardment of electrons on the substrate 614. The electrode606 and the conduit 610 are surrounded by an insulating material 608,such as a dielectric material, to electrically isolate the electrode 606and conduit 610 from the pedestal 604.

An actuator 644 is coupled to the pedestal 604 and is configured toraise and lower the pedestal 604 within the process volume 640. Theactuator 644 may also cause the pedestal to rotate about a verticalaxis. A bellows assembly 642 is disposed about a portion of the pedestal604 which extends through the chamber body 602 and the bellows assembly642 is operable to enable vertical movement of the pedestal 604 whilemaintaining a process environment of the process volume 640. Forexample, the bellows assembly 642 may be operable to maintain asub-atmospheric pressure process environment within the process volume640 while the pedestal 604 is raised or lowered.

A first gas source 630 is in fluid communication with the process volume640 via a first conduit 628 extending through the chamber body 602. Inone embodiment, the first gas source 630 is an inert gas source whichsupplies an inert gas, such as argon or helium, to the process volume640. A second gas source 634 is in fluid communication with the processvolume 640 via a second conduit 632 extending through the chamber body602. In one embodiment, the second gas source 634 is a process gassource which supplies a process gas, such as a chlorine containing gas,a fluorine containing gas, a bromine containing gas, oxygen containinggas, or the like, to the process volume 640.

In an alternate embodiment, the first gas source 630 and second gassource 634 may be in fluid communication with the process volume 640 viaan electrode 618. In this embodiment, the conduits 628, 632,respectively, are coupled between the gas sources 630, 634 and theprocess volume 640 via the electrode 618. For example, the conduits 628,632 may extend through the electrode 618 or the second electrode 618 mayinclude a plurality of apertures to function as a gas deliveryshowerhead. The apertures may be disposed on the angled surfaces 621 toprovide a flow patch of the gas from the gas sources 630, 634 into theprocess volume 640.

The electrode 618 is coupled to the lid 616 and the electrode 618 isoriented opposite the electrode 606. The electrode 618 includes asegmented surface 620 which includes a plurality of angled surfaces 621.In one embodiment, the substrate 614 is disposed on the electrode 606 ofthe pedestal 604 in a substantially horizontal orientation. In such anembodiment, the angled surface 621 are oriented in an angled andnon-parallel orientation relative to either the substrate 614 or a majoraxis (horizontal) of the electrode 606. In the illustrated embodiment,the angled surface 621 of the segmented surface 620 are substantiallyuniform across the electrode 618. Alternatively, the angled surfaces 621of the segmented surface 620 may be non-uniform. For example, the angledsurface 621 may have different angles or may be positioned, spaced, orotherwise oriented in a non-uniform manner to enable fabrication ofwaveguides with non-uniform gratings.

A conduit 624, such as an electrical conduit or the like, is coupledbetween the electrode 618 and a power source 626. The electrode 618 andconduit 624 are surrounded by an insulating material 622, such as adielectric material, to electrically isolate the electrode 618 andconduit 624 from the lid 616.

In operation, a plasma is generated in the process volume 640 by variousbulk and surface processes, for example, by capacitive coupling. In thisembodiment, the power source 626 is a radio frequency (RF) power source.The power source 626 is operable to generate RF power having a frequencyof about 13.56 MHz or about 2 MHz, depending upon desired electron beamcharacteristics. For example, RF power is applied in a constant orpulsed manner to the electrode 618 and the electrode 606 is biasedrelative to the electrode 618. In another example, RF power is appliedto the electrode 618 and the electrode 606 remains unbiased. It isbelieved that ions generated by a capacitively coupled plasma areinfluenced by an electric field that encourages bombardment of theelectrode 618 by the ions generated from the plasma. Other plasmageneration processes, such as a hollow cathode arrangement, directcurrent electrode biasing, or electron beam plasma generation processesmay be utilized in accordance with the embodiments described herein.

Ion bombardment energy of the electrode 618 and density of the plasmaformed in the process volume 640 are controlled, at least in part, bythe power source 626 (e.g. RF power source). Ion bombardment of theelectrode 618 is believed to heat the electrode 618 and cause theelectrode 618 to emit secondary electrons. In one embodiment, theelectrode 618 is fabricated from a process compatible material having ahigh secondary electron emission coefficient, such as silicon, carbon,silicon carbon material, or silicon oxide materials. The electrode 618may also be fabricated from a metal oxide material such as aluminumoxide, yttrium oxide, or zirconium oxide.

Energetic secondary electrons, which have a negative charge, are emittedfrom the segmented surface 620 at angles influenced by the angledsurface 621 and accelerated away from the electrode 618 due to biasingof the electrode 618. In this example, the electrode 618 may benegatively biased. The angled surfaces 621 of the segmented surface 620are oriented at an angle between about 1° and about 75° relative to ahorizontal datum plan defined by the electrode 606. As such, an electronbeam 660 is accelerated from the electrode 618 at a non-normal anglerelative to the electrode 606 and the substrate 614.

The flux of energetic electrons from the segmented surface 620 of theelectrode 618 is an electron beam. A beam energy of the electron beam660 is approximately equal to the ion bombardment energy of theelectrode 618. In one embodiment, the plasma potential is greater thanthe potential of the electrode 618 and the energetic secondary electronsemitted from the electrode 618 are further accelerated by a sheathvoltage of the plasma as the secondary electrons of the electron beam660 traverse through the plasma formed in the process volume 640.

At least a portion of the electron beam 660, comprised of the secondaryelectron flux emitted from the electrode 618 due to energetic ionbombardment of the segmented surface 620, propagates through the processvolume 640 and contacts the substrate 614 to etch the substrate 614. Inone embodiment, the electron beams 660, in addition to the capacitivelygenerated plasma, generate chemically reactive radicals and ions whichmay adsorb to the surface of the substrate 614 and form a chemicallyreactive layer on the surface of the substrate 614.

FIG. 7A illustrates an angled etching process performed on the substrate210 at a first position according to an embodiment of the disclosure.The substrate 210 has the grating material 212 disposed thereon and thepatterned hardmask 213 is disposed on a surface 702 of the gratingmaterial 212. In the illustrated embodiment, the substrate 210 ispositioned a first distance 710 from the segmented ion source 230, suchas the segmented ion sources described with regard to the ion beamsystem 200 of FIGS. 2-5B. In another embodiment, the substrate 210 maybe processed by the system 600 utilizing the segmented surface 620 ofthe electrode 618 to generate an electron beam to etch the gratingmaterial 212.

The ion beam 216 (or electron beam 660) is directed toward the substrate210 at a non-normal angle relative to a major axis of the substrate 210.The patterned resist 213 exposes certain regions at the surface 702 ofthe grating material 212 which is etched by the ion beam 216 or electronbeam 660. As a result, recesses 704 and fins 706 are formed in thegrating material 212. While only two fins 706 and three recesses 704 areillustrated, the entire grating material 212 or desired portions thereofmay be etched to form the recesses 704 and fins 706 depending upon thedesired grating design for the waveguide to be fabricated. The fins 706and recesses 704 collectively comprise a grating.

FIG. 7B illustrates the substrate 210 of FIG. 7A during the angledetching process at a second position according to an embodiment of thedisclosure. The second position locates the substrate 210 a seconddistance 720 from the segmented ion source 230 (or segmented surface 620of the electrode 618). In one embodiment, the second distance 720 isless than the first distance 710. In another embodiment, the seconddistance 720 is greater than the first distance 710. The substrate 210may be elevated from the first distance 710 to the second distance 720by the platen 206 or pedestal 604 depending upon the apparatus 200, 600utilized. By changing the distance, etching and beam exposurecharacteristics are changed which result in different etching profilesof the grating material 212. For example, certain recesses 704 mayextend deeper into the grating material 212 from the surface 702 whileother recesses are more shallow. Thus, the fins 706 may have differentmagnitudes and may modulate light propagating through the waveguide.

FIG. 8 illustrates operations of a method 800 for etching a waveguidewith an angled ion beam according to an embodiment of the disclosure. Atoperation 802, a waveguide (or substrate, such as the substrate 216, tobe fabricated into a waveguide) is positioned on a platen. In oneexample, the waveguide is positioned on the platen 206. At operation804, the platen is positioned a first distance from an angled ion beamsource. For example, the platen 206 is positioned a first distance 710from the segmented ion source 230.

At operation 806, ions are projected from the angled ion beam sourcetoward the waveguide to form fins having a first depth. At operation808, the platen is positioned a second distance from the angled ion beamsource. The second distance is different from the first distance. In oneexample, the platen 206 is positioned the second distance 720 from thesegmented ion source 230. At operation 810, ions are projected from theangled ion beam source toward the waveguide to form fins having a seconddepth different from the first depth. The depth of the fins 706 concernsthe distance the fins 706 extend into the grating material 212 and alsocorrelates to the depth of the recesses 704. In one embodiment, thesecond depth is greater than the first depth. In another embodiment, thesecond depth is less than the first depth.

FIG. 9 illustrates operations of a method 900 for etching a waveguidewith an angled electron beam according to an embodiment of thedisclosure. At operation 902, a waveguide (or substrate, such as thesubstrate 216, to be fabricated into a waveguide) is positioned on aplaten. In one example, the waveguide is positioned on the pedestal 604.At operation 904, the platen is positioned a first distance from anangled electron beam source. For example, the pedestal 604 is positioneda first distance 710 from the segmented surface 620 of the electrode618.

At operation 906, electrons are projected from the angled electron beamsource toward the waveguide to form fins having a first depth. Atoperation 908, the platen is positioned a second distance from theangled electron beam source. The second distance is different from thefirst distance. In one example, the pedestal 604 is positioned thesecond distance 720 from the segmented surface 620 of the electrode 618.At operation 810, electrons are projected from the angled electron beamsource toward the waveguide to form fins having a second depth differentfrom the first depth. The depth of the fins 706 concerns the distancethe fins 706 extend into the grating material 212 and also correlates tothe depth of the recesses 704. In one embodiment, the second depth isgreater than the first depth. In another embodiment, the second depth isless than the first depth.

The methods 800, 900 respectively enable waveguide fabrication utilizingion and electron beams. It is contemplated that the methods 800, 900 mayutilize a single etching cycle or multiple etching cycles. In oneexample, a 45° angled etching process may be performed about 14 timesfor a duration of about 300 seconds per time. In this example, anapproximately 240 nm deep recess was formed with an etching rate ofabout 3 nm/min. In another example, a 60° angled etching process may beperformed for about 18 times for a duration of about 300 seconds pertime. In this example, an approximately 190 nm deep recess was formedwith an etching rate of about 1.8 nm/min. However, it is contemplatedthat the apparatus and methods described herein may enable etching ratesup to about 50 nm/min, depending upon the process variables of the ionor electron beam etching process and the desired angle of etch.

The methods 800, 900 may be utilized for blanket substrate etches oversubstantially the entire substrate surface or for more localized etchingprocesses when specified regions of the substrate are etchedpreferentially to other regions. The segmented ion source 230 andsegmented surface 620 of the electrode 618 enable improved angledetching efficiency with ion and electron beams, respectively. It is alsocontemplated that segmented ions sources 230 and segmented surfaces 620of the electrode 618 may be swapped out of their respective systems 200,600 to more efficiently change etching profiles of waveguides whichembody gratings having a plurality of fin heights and recess or trenchdepths or with gratings of different angles.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A waveguide fabrication method, comprising:positioning a substrate on a pedestal in a process volume of a chamber;positioning the pedestal opposite a segmented surface of an electrode,the segmented surface comprising a plurality of angled surfaces; andprojecting electrons from the segmented surface of the electrode towardthe substrate at one or more non-normal angles to form angled fins onthe substrate.
 2. The method of claim 1, further comprising: positioningthe pedestal a first distance from the segmented surface during theprojecting the electrons from the segmented surface; and forming angledfins having a first depth.
 3. The method of claim 2, further comprising:positioning the pedestal a second distance from the segmented surface;projecting electrons from the segmented surface; and forming angled finshaving a second depth.
 4. The method of claim 3, wherein the seconddistance is different than the first distance.
 5. The method of claim 4,wherein the second distance is less than the first distance.
 6. Themethod of claim 4, wherein the second distance is greater than the firstdistance.
 7. The method of claim 3, wherein the second depth isdifferent than the first depth.
 8. The method of claim 7, wherein thesecond depth is greater than the first depth.
 9. The method of claim 7,wherein the second depth is less than the first depth.
 10. The method ofclaim 1, wherein the electrons are projected toward the substrate atsubstantially uniform angles.
 11. The method of claim 1, wherein theelectrons are projected toward the substrate at different angles fordifferent regions of the substrate.
 12. A waveguide fabrication method,comprising: positioning a substrate on a pedestal in a process volume ofa chamber; positioning the pedestal opposite a segmented surface of anelectrode, the segmented surface comprising a plurality of angledsurfaces having a substantially uniform morphology; generating a plasmain the process volume; and projecting electrons from the segmentedsurface of the electrode toward the substrate at one or more non-normalangles to form angled fins on the substrate.
 13. The method of claim 12,further comprising: positioning the pedestal a first distance from thesegmented surface during the projecting the electrons from the segmentedsurface; and forming angled fins having a first depth during a firstetching process.
 14. The method of claim 13, further comprising:positioning the pedestal a second distance from the segmented surface;projecting electrons from the segmented surface; and forming angled finshaving a second depth during a second etching process.
 15. The method ofclaim 12, further comprising: chucking the substrate to an electrodedisposed in the pedestal.
 16. The method of claim 12, wherein theelectrons are projected at an angle of between about 1° and about 75°relative to a plane defined by the electrode disposed in the pedestal.17. A waveguide fabrication method, comprising: positioning a substrateon a pedestal in a process volume of a chamber; positioning the pedestalopposite a segmented surface of an electrode, the segmented surfacecomprising a plurality of angled surfaces having different morphologiesand differing in at least one of size, shape, spacing, density ordistribution across the segmented surface; generating a plasma in theprocess volume; and projecting electrons from the segmented surface ofthe electrode toward the substrate at one or more non-normal angles toform angled fins on the substrate.
 18. The method of claim 17, furthercomprising: positioning the pedestal a first distance from the segmentedsurface during the projecting the electrons from the segmented surface;and forming angled fins having a first depth during a first etchingprocess.
 19. The method of claim 18, further comprising: positioning thepedestal a second distance from the segmented surface; projectingelectrons from the segmented surface; and forming angled fins having asecond depth during a second etching process.
 20. The method of claim19, wherein the second depth is different from the first depth.